Communications devices often need to exchange information by interconnecting each other. As shown in FIG. 1, FIG. 1 shows a typical scenario of an interconnection between communications device subracks, where the communications device subracks include one main subrack and three service subracks (a service subrack 1, a service subrack 2, and a service subrack 3), each subrack has one switch board, and a switch board of a service subrack is connected to a switch board of a main subrack by using one Ethernet interface, so as to implement service convergence.
Allocation of an interface for an interconnection of communication devices often needs to comply with a certain rule, for example, one device must be connected to a specified interface of another device and cannot be arbitrarily connected to any one of a plurality of interfaces; or a plurality of interfaces of a device has different function definitions, for example, some interfaces are used to access signaling, some interfaces are used to access data, but mixed insertion is not allowed, otherwise, a normal service operation is affected. Besides a scenario where a fault easily occurs during initial installation, another scenario where a fault easily occurs is if a device is connected to many network cables, when the device fails, network cables need to be unplugged and then a new device is placed, and finally the network cables are plugged again, and in this case, network cables are also possibly connected in wrong positions. Under the two situations, a connection state of a network port (namely, a network port remains linked up) is not affected even if the network cables are connected in wrong positions and a problem is discovered only when a service starts to operate, but a basic reason is difficult to be recognized. As a result, a method for preventing mixed insertion of network cables is required.
To prevent a problem of mixed insertion of network cables, in a first prior art, a foolproof design is performed on a connector, so that mixed insertion is avoided by designing different shapes and structures of connectors. For example, a network port usually uses a RJ45 connector, a serial port usually uses a DB9 connector, and they are incompatible in shape. Therefore, mixed insertion may not occur. However, this manner is inapplicable to a case in which a device has a large number of interfaces of a same type.
Further, in a second prior art, a color matching design is performed on a connector and an electric cable, and mixed insertion is avoided by designing a same color for the connector and a matched electric cable. However, in this manner, many connectors and electric cables of a same type but of different colors are formed, and they are incompatible with each other, which increases a device cost.
In addition, in a third prior art, a connection relationship of different interfaces is instructed in a user manual, and meanwhile each interface name is marked on a device to distinguish network cables. However, the manner that wholly relies on a manual operation does not ensure accuracy of a connection.